Kinetic Studies in the Chemistry of Rubber and Related Materials. II. The Kinetics of Oxidation of Unconjugated Olefins

1947 ◽  
Vol 20 (3) ◽  
pp. 609-617 ◽  
Author(s):  
J. L. Holland ◽  
Geoffrey Gee
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Studies ◽  
Chain Termination ◽  
Low Oxygen ◽  
Chain Reaction ◽  
Kinetics Of Oxidation ◽  
Chain Initiation ◽  
A Chain ◽  
Kinetics Of ◽  
Direct Attack

Abstract A brief review is given of kinetic work on the oxidation of representative mono, 1,4 and 1,5 olefins. The essential process in each case is identified as a chain reaction in which hydrocarbon radicals are formed, absorb oxygen, and then react with another molecule of olefin to give a hydroperoxide and a new free radical. Three methods of chain initiation are considered: (1) direct attack of oxygen on the olefin, (2) thermal decomposition of the hydroperoxide, (3) thermal decomposition of added benzoyl peroxide. Chain termination results from interaction of two free radicals; except at low oxygen pressures, these are both peroxidic.

THE KINETICS OF THE THERMAL DECOMPOSITION OF DISULPHUR DECAFLUORIDE

1951 ◽  
Vol 29 (6) ◽  
pp. 508-525 ◽  
Author(s):  
W. R. Trost ◽  
R. L. McIntosh
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Heterogeneous Reaction ◽  
Homogeneous Reaction ◽  
Chain Reaction ◽  
First Order ◽  
Reaction Proceeds ◽  
Total Process ◽  
A Chain ◽  
Kinetics Of

The thermal decomposition of the gas disulphur decafluoride has been studied in a metal reactor. Analytical evidence showed that the reaction proceeds according to the equation S2F10 = SF6 + SF4.The reaction was found to be largely homogeneous, as the heterogeneous reaction accounted for less than 5% of the total process. The homogeneous reaction was shown to be first order, and in the temperature range investigated the rate is given by ln k = 47.09 − 49,200/RT. A chain reaction is postulated to explain the observed rate of the reaction. The effect of nitric oxide and acetylene dichloride on the rate and products of the reaction was investigated.

scholarly journals Kinetic studies in the chemistry of rubber and related materials. I. The thermal oxidation of ethyl linoleate

1946 ◽  
Vol 186 (1005) ◽  
pp. 218-236 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Reaction Mechanism ◽  
Thermal Oxidation ◽  
Molecular Oxygen ◽  
Kinetic Studies ◽  
Ethyl Linoleate ◽  
Chain Termination ◽  
Radical Chain ◽  
Kinetics Of ◽  
Sole Product

The kinetics of the initial stages of the thermal oxidation of ethyl linoleate (by molecular oxygen) have been investigated in the temperature range 35—75° C. From consideration of chemical and kinetic evidence the reaction mechanism has been established: oxidation chains are initiated by thermal decomposition of ethyl linoleate hydroperoxide (which in the early stages of oxidation is substantially the sole product). The chain propagation reactions are identified as R — + O 2 → R O 2 — and R O 2 — + R H → R OOH + R — (where R H represents ethyl linoleate). Chain termination occurs by mutual destruction of the radical chain carriers, R — and R O 2 — .

scholarly journals Kinetics and Mechanism of Oxidation oft-Butylbenzylamine by Diperiodatoargentate(III) in Aqueous Alkali

2012 ◽  
Vol 9 (1) ◽  
pp. 203-210 ◽  
Author(s):  
Mahantesh A. Angadi ◽  
Suresh M. Tuwar
Keyword(s):  
Kinetic Studies ◽  
Active Species ◽  
Alkali Concentration ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Middle Range ◽  
Wide Range ◽  
Rate Of Reaction ◽  
Mechanism Of Oxidation ◽  
Kinetics Of

t-Butylbenzylamine (t-BA) is used as a free base in the synthesis of salbutamol drug. Its mechanism of oxidation was proposed from kinetic studies. The kinetics of oxidation oft-butylbenzylamine by diperiodatoargentate(III) (DPA) was studied spectrophotometrically by monitoring decrease in absorbance of DPA. The reaction was found to be first order each in [DPA] and [t-BA]. The effect of alkali concentration in a wide range on rate of reaction was studied. The rate of reaction was found to be increased with increase in [OH–] in the lower range of [OH–], decreasing effect in the middle range and at higher range again increasing effect on rate of reaction was observed. The added periodate retarded the rate of reaction. The polymerization test revealed that oxidation was occurred with the intervention free radical. A suitable mechanism was proposed for a middle range of [OH–]. The active species of silver(III) periodate for all the three different stages of [OH–] are assayed. Rate law was derived and verified. The oxidative product oft-BA was characterized by LC-ESI-MS spectra.

The thermal decomposition of aliphatic aldehydes

1963 ◽  
Vol 276 (1365) ◽  
pp. 278-292 ◽  
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Chain Reaction ◽  
Chance Coincidence ◽  
Limited Success ◽  
Molecular Reaction ◽  
A Chain ◽  
The Stability ◽  
Oxide Inhibition ◽  
Chain Propagation And Termination

The thermal decomposition of acetaldehyde, propionaldehyde, n -butyraldehyde and iso-butyraldehyde, as investigated by the static method, is essentially homogeneous, inhibitable by propylene, isobutene and small amounts of nitric oxide, and generally catalyzed at high inhibitor concentrations. The kinetic order of the uninhibited decomposition exhibits little obvious regularity, but that of the maximally inhibited reaction is approximately 1.5 for all three inhibitors. Kates of the uninhibited decomposition do not follow the sequence in the homologous series, and there is no systematic variation in the extent of inhibition from one aldehyde to another. For each aldehyde, the minimum rates for the three inhibitors in general are not identical, nevertheless exhibit a correspondence probably close enough to eliminate chance coincidence. The kinetic and analytical results of the uninhibited decomposition can be approximately described by a Kice-Herzfeld-type mechanism, with the kinetics in each case largely determined by the stability of radicals and their reactions in chain propagation and termination. The question whether the maximally inhibited reaction is a molecular reaction or a chain reaction is surveyed. Although the results cannot be completely accounted for by a molecular reaction alone, a chain mechanism for propylene inhibition involving allyl radicals likewise has only limited success. For nitric-oxide inhibition, it is not certain how far the results are affected by the occurrence of the subsequent catalyzed reaction. No definite conclusion can thus be reached about the nature of the maximally inhibited reaction.

scholarly journals The kinetics of the combustion of methane

1936 ◽  
Vol 157 (892) ◽  
pp. 503-525 ◽  
Keyword(s):  
Induction Period ◽  
Time Curve ◽  
Kinetics Of Oxidation ◽  
Reaction Velocity ◽  
Oxidation Of Methane ◽  
Pressure Time ◽  
Reactive Mixture ◽  
A Chain ◽  
Combustion Processes ◽  
Kinetics Of

The kinetics of oxidation of methane at pressures comparable with atmospheric pressure presents many features of great interest and of considerable importance to the elucidation of the nature of combustion processes in general. The facts which have accumulated to date, though fairly precise and definite, require in some cases amplification and further study in view of the realization that combustion has the character of a chain reaction. It has been found that the temperature of ignition of methane, which lies in the region 700-800°C., is dependent on the composition and total pressure of the mixture. For equimolecular mixtures of CH 4 and O 2 , no lower limit phenomena of the kind associated with hydrogen or carbon monoxide ignition have been observed. Below the ignition limit there is a readily measurable reaction velocity, and it was shown by Fort and Hinshelwood that the pressure-time curve is comprised of three distinct parts: ( a ) an induction period of several seconds’ or minutes’ duration, during which almost no reaction can be detected; ( b ) a period of acceleration to a steady velocity, followed by ( c ) a gradual decline of the velocity to zero as the reactants are used up. Fort and Hinshelwood showed that the velocity during the reaction period was much more dependent on the pressure of methane than that of oxygen. They further established the fact that the reaction is almost completely inhibited by packing the vessel with pieces of quartz tubing. Bone and Allum showed that the most reactive mixture consists of methane and oxygen in the ratio 2:1, the induction period being shortest and the reaction velocity greatest for this proportion. It was further found that the reaction is subject to sensi­tization, small quantities of nitrogen peroxide, iodine, or formaldehyde practically removing the induction period and increasing the reaction rate. An analysis of the products of the reaction showed that it followed the general course: CH 4 + 1½ O 2 = 2H 2 O + CO. (I)

scholarly journals Membrane-bound ribosomes of myeloma cells. II. Kinetic studies on the entry of newly made ribosomal subunits into the free and the membrane-bound ribosomal particles.

1975 ◽  
Vol 67 (1) ◽  
pp. 16-24 ◽  
Author(s):  
B Mechler ◽  
P Vassalli
Keyword(s):  
Messenger Rna ◽  
Specific Radioactivity ◽  
Kinetic Studies ◽  
Chain Termination ◽  
High Turnover ◽  
Ribosomal Subunits ◽  
Myeloma Cells ◽  
High Specific Radioactivity ◽  
Membrane Bound ◽  
Kinetics Of

The kinetics of appearance of newly made 60S and 40S ribosomal subunits in the free and membrane-bound ribosomal particles of P3K cells were explored by determining the specific radioactivities of their 18S and 28S RNA after various lengths of [3H]uridine pulse. Both 40S and 60S subunits enter free and membrane-bound polyribosomes at comparable rates from the cytoplasmic pool of newly made, free native subunits, the 40S subunits entering the native subunit pool and the polyribosomes slightly earlier than the 60S subunits. At all times, the specific radioactivity of the membrane-bound native 60S subunits was slightly lower than that of the polyribosomal 60S subunits. This indicates that the membrane-bound native 60S subunits are not precursors destined to enter membrane-bound polyribosomes and suggests that they result from the dissociation of ribosomes after chain termination. The results observed also suggest that the membrane-bound native 60S subunits are not reutilized before their release from the membranes, which probably takes place shortly after dissociation from their 40S subunits. The monoribosomes, both free and membrane-bound, had the lowest specific radioactivities in their subunits. Finally, a small amount of newly made native 40S subunits, containing 18S RNA of high specific radioactivity, and apparently also newly made messenger RNA were detected on the membranes. The high turnover of these membrane-bound native 40S subunits suggests that they may represent initiation complexes formed with mRNA which has just reached the membranes and which has not yet given rise to polyribosomes.

The kinetics of the thermal decomposition of normal paraffin hydrocarbons II. Comparative measurements on the series from propane to n -decane

1950 ◽  
Vol 201 (1064) ◽  
pp. 18-26 ◽  
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
High Pressures ◽  
Single Mode ◽  
Second Order ◽  
Chain Reaction ◽  
Molecular Rearrangement ◽  
Normal Paraffin ◽  
Rearrangement Process ◽  
Kinetics Of

The rates of the nitric oxide-inhibited decompositions of hydrocarbons in the series propane to n -decane (which according to the results of Part I represent the chain-free molecular reactions) have been measured over a range of pressures. As inferred from the 'apparent chain length' the molecular rearrangement process increases in importance relatively to the chain reaction with the ascent of the series, and, for a given hydrocarbon, with increasing pressure. For each hydrocarbon, the order of reaction varies between the first and the second. The results are not consistent with a constant order of 1.5 as has been suggested. Nor is the pressure dependence consistent with the uniform transition from second order to first predicted for unimolecular reactions dependent upon a single mode of activation by collision. There appears to be a contribution to the overall reaction from processes which remain of second order up to high pressures. The decomposition rate for a given hydrocarbon pressure tends to a limit as the series is ascended, for reasons which are discussed.

The kinetics of the thermal decomposition of normal paraffin hydrocarbons - I. The inhibition of chains and the nature of the residual reaction

1950 ◽  
Vol 200 (1063) ◽  
pp. 458-473 ◽  
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Steady State ◽  
Chain Reaction ◽  
Normal Paraffin ◽  
Residual Rate ◽  
Molecular Reaction ◽  
Kinetics Of ◽  
Limiting Value

The decomposition of paraffin hydrocarbons is lowered to a limiting value by additions of nitric oxide or of propylene. It has been a matter for discussion whether the residual rate corresponds to a molecular reaction or a steady state in which the chain reaction is imperfectly suppressed. Fresh evidence, including the facts that the limiting rates with the two inhibitors are identical, and that extra nitric oxide added during the reaction has no further effect, indicates that the former hypothesis is the more probable.

Thermal decomposition of barium perchlorate

1969 ◽  
Vol 47 (16) ◽  
pp. 3031-3039 ◽  
Author(s):  
R. J. Acheson ◽  
P. W. M. Jacobs
Keyword(s):  
Thermal Decomposition ◽  
Ambient Pressure ◽  
Barium Chloride ◽  
Reaction Sequence ◽  
Chain Reaction ◽  
Gaseous Products ◽  
A Chain ◽  
Two Stages ◽  
Linear Period ◽  
Barium Perchlorate

The thermal decomposition of anhydrous barium perchlorate to barium chloride and oxygen has been studied by pressure measurements, or by weight loss, in vacuo, under the accumulated gaseous products (0–3 Torr oxygen), under dry air or nitrogen, and mixed with added barium chloride. The plots of fractional decomposition (α) against time (t) are complex, as would be expected for a reaction proceeding via unstable intermediates. The most pronounced features of the α(t) curves are an initial acceleratory period, which is succeeded by an approximately linear period and then, after a sharp break (reduction in rate), by a deceleratory period which conforms to the contracting-volume kinetic law. The latter stage is associated with the decomposition of barium chlorate and has an activation energy of 59 kcal/mole. The first two stages comprise the decomposition of perchlorate to chlorate with the approximate stoichiometry 3ClO4− = 2ClO3− + Cl− + 3O2. A chain reaction sequence, which involves O atoms as chain carriers, is proposed for these stages. The effect of the removal of products, of increasing the ambient pressure of inert gas, and of the addition of barium chloride, can all be explained on this model.

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